fix: prevent Enter/Space from propagating from Grid

[microbit-matt-hillsdon]

The basics

• I validated my changes

The details

Resolves

See RaspberryPiFoundation/blockly-keyboard-experimentation#618
This is a narrower fix than the one on RaspberryPiFoundation/blockly-keyboard-experimentation#619

Proposed Changes

Prevent Enter/Space from propagating from Grid so it is not inappropriately handled by other listeners, e.g. the keyboard navigation plugin.

Reason for Changes

Test Coverage

Documentation

Additional Information

[maribethb]

Can you do the e.stopPropagation inside the click event handler for the grid_item instead? That's what I was originally thinking, but I guess I don't know if that works for stopping the keyboard event too since that event being fired on enter is browser behavior due to being a button.

[microbit-matt-hillsdon]

Can you do the e.stopPropagation inside the click event handler for the grid_item instead? That's what I was originally thinking, but I guess I don't know if that works for stopping the keyboard event too since that event being fired on enter is browser behavior due to being a button.

I don't think so because the keydown event (including propagation) happens before the click event.
Demo: https://jsfiddle.net/hsatg5un/

This is part of why I think this change is OK if we want it in Blockly field editors, but it's not really a reasonable ask of all field editors.

[maribethb]

Thanks for the demo, that's unfortunate. That definitely makes sense why we wouldn't want to ask everyone to do it. I'm not sure if we should even do it, but it's probably worth it to make it easier to write custom keyboard shortcuts.

[cpcallen]

Sorry, I completely forgot that I also needed to hit merge!